This invention relates generally to computers, and more specifically to a system and method for cooling computers which are wearable on the body of a user.
As personal computers have become more popular in everyday life, they have also become more indispensable in the daily activities of a computer user. As such, many computer users desire almost constant access to their computers. As technology and communications advance and more goods and services are available through the use of a computer, such as over the Internet, the desire for constant access will continue to increase among computer users.
Conventionally, computers utilized by individuals and businesses are stand-alone devices which are generally permanently placed on a desk top, table top, or other support surface. While they may be readily moved from place to place, they are not meant to be constantly carried around by the user. To address the need for portability, portable computers are available which are carried by the user, generally in a specially made suitcase or bag. Existing portable computers continue to decrease in size and weight, but are still designed to be carried like luggage in a separate bag or other container and are then used by placing them on an available flat surface, such as a desk top.
Recently, wearable computers have become available. Wearable computers, such as a wearable personal computer, are worn or carried, and also used, on the body of the user. Therefore, the wearable computer is usually carried around without having to be stowed in a bag and hand-carried like luggage. Furthermore, a wearable computer is more likely to be used while being worn, rather than being taken off and placed on a support surface. This arrangement provides the user with greater mobility, convenience, and flexibility in the use of their computer.
As with other computers, a wearable computer has internal electronic components which generate heat during their operation and the operation of the computer. In particular, the processor component(s) of a computer consumes a significant amount of power and thus generates a substantial amount of heat. Consequently, the electronic components, and particularly processor components, must be cooled for proper operation. In addition to ensuring proper operation of internal electronic components, wearable computers also must be cooled sufficiently to ensure the comfort of the wearer. Unlike desktop or portable computers, wearable computers will generally be in contact with the user""s body and possibly their bare skin. In existing computers, an internal air moving device, such as an internal fan, is utilized to direct cooling air over the heat-generating components to cool those components. However, existing air moving and cooling systems for computers, while functional for conventional desktop or portable computers, have certain drawbacks with respect to their incorporation into a wearable computer.
Specifically, internal air moving devices, like fans, require relatively large airflow openings in the body or housing of the computer for feeding and exhausting air to and from the internal volume of the computer to cool the electronic components. Relatively large air flow openings and fans are suitable for existing desktop and portable computers, because those forms of computers will primarily be used indoors and thus are not significantly exposed to outside environmental elements, such as water and dirt. However, wearable computers are worn by a user and are therefore exposed to the environmental elements to which the user is exposed. Consequently, a wearable computer will be exposed to water, dirt, and other contaminant elements more frequently than other forms of a computer. Large airflow openings and fans which draw air through the openings also allow the water, dirt, and other contaminating elements into the internal volume of the computer and expose the electronic components to such contaminating elements. Any contamination or corrosion from exposure to environmental elements may impede the operation of the computer or even permanently damage it. Therefore, while traditional fan systems may be used to cool a wearable computer, they present contamination and operational risks.
Some versions of wearable computers have been cooled without an internal fan. However, those designs still use relatively large airflow openings. Furthermore, the convective heat transfer between the air surrounding the components and the computer body is very inefficient. This inefficiency results in higher internal temperatures and less reliable operation.
Therefore, it is an objective to improve the design and operation of computers, and more specifically to improve the cooling characteristics of a wearable computer.
It is another objective to reduce and eliminate exposure of the electronic components of a wearable computer to environmental elements which may adversely affect the operation of the computer.
It is still another objective to provide a comfortable computer for a user to wear without exposing the user to uncomfortably hot surfaces.
These objectives and other objectives of the present invention will become more readily apparent from the further description of the invention below.
In accordance with the above objectives and other objectives, the present invention provides a computer, or more specifically, a wearable computer, which does not utilize an internal fan or large openings in the body thereof for contaminants to enter. The computer comprises a chassis having an inner surface and an outer surface, and at least one processing device, such as a processor, or other heat-generating electronic component contained within the chassis. A portion of the chassis inner surface is positioned proximate to the processing device, and is thermally coupled to the processing device through a sheet of thermally conductive interface material. The sheet of thermally conductive interface material is preferably compliant, and is positioned between and simultaneously contacts the processing device and the inner surface portion. The compliant interface material is preferably pressed or squeezed between the processing device and chassis inner surface portions to provide efficient thermal coupling of the processing device to the chassis. In that way, heat generated by the processing device is conductively delivered to the chassis where it is further dissipated. The chassis is formed of a material with good thermal conductivity, such as aluminum or magnesium.
In accordance with another aspect of the present invention, an outer surface of the chassis is configured for dissipating heat from the chassis and, in one embodiment, includes a plurality of fins which are configured to convectively dissipate heat from the chassis. The fins may be shrouded with a shroud or other cover, which is configured to form a restricted air passage and to define inlets and an exhaust opening for more efficient convective airflow across and around the fins. The shroud may be formed of a thermally insulative material, such as a suitable plastic, for preventing contact between a user""s skin and the heated fins. The shroud may simply be part of the computer chassis or may house additional components, such as a battery.
In accordance with another aspect of the present invention, to further improve heat dissipation from the processing device, an amount of phase-change material is positioned on the inner surface of the chassis proximate the processing device. The phase-change material, for example, paraffin, is operable for absorbing heat from the processing device and changing phase (e.g. from solid to liquid) upon absorption of an amount of heat. The phase-change material assists the chassis in removing heat from the processing device, such as when the efficient convection and dissipation of heat through the fins is compromised or interrupted due to the position of the computer chassis and the finned outer surface.
In accordance with another aspect of the present invention, additional electronic and/or processing devices within the computer which generate heat when operating are thermally coupled to a heat pipe, such as a copper heat pipe. The heat pipe is also thermally coupled to the chassis to absorb heat from the electronic devices and transfer the heat to the chassis to be dissipated. In one embodiment of the invention, the heat pipe is a copper heat pipe in the form of a ribbon wherein one side or surface of the heat pipe is adhesively coupled to the electronic devices, and wherein the other side or surface of the heat pipe is adhesively coupled to an inner surface of the chassis.
The multiple cooling elements and the system of the present invention provide for effective and safe dissipation of heat from the computer so the computer may be worn comfortably while its internal temperature, and the temperature of the internal electronic devices, is maintained within a proper operational range. The present invention provides for efficient heat transfer while reducing the number of openings within the computer through which water, dirt, and other contaminating elements may pass. Therefore, the contamination of the internal electronic components, and the degradation of their operation, is reduced.